1. Field of the Invention
The present invention relates to a semiconductor light emitting device including an active layer formed of a group III nitride semiconductor, and particularly relates to a semiconductor light emitting device using a nonpolar plane or a semipolar plane as a growth principal surface.
2. Description of the Related Art
A semiconductor light emitting device formed of a group III nitride semiconductor is used for a light emitting diode (LED) and the like. As examples of the group III nitride semiconductor, there are aluminum nitride (AlN), gallium nitride (GaN), indium nitride (InN) and the like. A typical group III nitride semiconductor is represented as AlxInyGa1-x-yN (0≦x≦1, 0≦y≦1, 0≦x+y≦1). The gallium nitride (GaN) is a group III nitride semiconductor that is well known among hexagonal compound semiconductors containing nitrogen.
In general, a semiconductor light emitting device using GaN has a structure in which an n-type GaN layer, an active layer (light emitting layer) and a p-type GaN layer are stacked on a GaN substrate, and emits light generated in the active layer to an outside of the semiconductor light emitting device. In recent years, use of a semiconductor light emitting device that emits a polarization has been advanced. If the semiconductor light emitting device that emits the polarization is used as a liquid crystal backlight or a projector light source, then a light component attenuated by a polarizer is reduced. As a result, efficiency of the liquid crystal backlight or the projector light source is enhanced.
A semiconductor light emitting device formed of a group III nitride semiconductor using a nonpolar plane or a semipolar plane as a growth principal surface emits the polarization. In a semiconductor light emitting device of the related art, side end surfaces thereof as cut surfaces when the semiconductor light emitting device is formed into a chip are not specular surfaces, since there is an advantage that a quantity of light extracted in the case where a light extraction surface is a rugged-state plane (rough plane) is large. However, the light extracted from the rough plane is random light owing to diffused reflection. As a result, a polarization direction of the polarization extracted from each of the side end surfaces of the semiconductor light emitting device is disturbed, and a polarization ratio of the polarization emitted from the semiconductor light emitting device is decreased.